Chapter 3 Objectives List the three parts of the cell theory. Section 2 Cell Features Objectives List the three parts of the cell theory. Determine why cells must be relatively small. Compare the structure of prokaryotic cells with that of eukaryotic cells. Describe the structure of cell membranes.

New Vocabulary Cell theory Cell membrane Cytoplasm Cytoskeleton Ribosome Prokaryote Cell wall Flagellum Eukaryote Nucleus Organelle Cilium Phospholipid Lipid bilayer

After Robert Hooke named the “cell” in 1665, it took many scientists who were working together ______ years to understand what a cell was Matthias _____________, a German botanist, viewed many plants under a microscope In 1838, he concluded that all plant parts are made of _______________ 150 Schleiden cells

1839 Schwann animal Virchow preexisting One year later, in ________, Theodore _________ concluded that all __________ parts are made of cells Hint…Schwann sounds like swan In 1858, Robert __________ determined that all cells come from _________________ cells that reproduced animal Virchow preexisting

cell theory made structure function preexisting Chapter 3 Section 2 Cell Features The work of these three scientists are the basis for the ___________________, which has three parts: 1. All living things are _________ of one or more cells. 2. Cells are the basic units of _____________ and _________________ in organisms. 3. All cells arise from ________________ cells. cell theory made structure function preexisting

efficiently volume surface area membrane parts Chapter 3 Cell Size Section 2 Cell Features Cell Size Cells cannot grow too large because small cells function more ________________ than large cells This is due to the fact that ________________ increases more quickly than _________________ efficiently volume surface area The surface area of this cube represents the cell ____________. Its volume contains all of its cell __________ membrane parts

If each side of the cube is 1mm long, what is its surface area? Find the area of one side and multiply by ____ to find the total area of all the sides Area = 1 mm x 1mm = _________ Surface area = ________ x _____ = 1 mm 6 1 mm2 1 mm2 6 6mm2

1mm 1mm 1mm 1mm3 6:1 Find the volume of this cube 1 mm Volume = length x width x height Volume = ____ x ____ x ____ = ______ So this cell’s surface area to volume ratio is… 1 mm 1mm 1mm 1mm 1mm3 6:1

Find surface area and volume for a cube with sides that are 2mm long S.A. = Volume = So the s.a. to volume ratio of this cube is… 2 mm 24 mm2 8 mm3 24:8 = 3:1

Find surface area and volume for a cube with sides that are 4 mm long S.A. = Volume = So the s.a. to volume ratio of this cube is… 4 mm 96 mm2 64 mm3 96:64 = 3:2

6 3 1.5 Ratios can also be written as fractions 1 mm 6:1 6/1 =

low If a cell’s surface area–to-volume ratio is too _____, substances cannot enter and leave the cell well enough to meet the cell’s needs. So if the cell grows too big, it won’t be able to get enough food _____ or waste ______ fast enough to survive in out

big park Think of yourself in a crowded park One park is small and one park is big, but they are both uniformly crowded or have the same density Will it take you longer to travel to the center of the small park or the big park? big park

The same applies for food particles in a cell, so large cells end up ______________ from lack of food or being ____________________ by waste starving poisoned

Question 1 Who studied plants…Schleiden or Schwann? Schleiden

Question 2 What are the three parts of the cell theory? All living things are made of one or more cells. Cells are the basic unit of structure and function in organisms. Cells come from preexisting cell.

Question 3 Why must cells be relatively small? Because volume increases faster than surface area, and if it gets too big, it will starve or be poisoned